Atherosclerotic disease can cause the build-up of plaque deposits in a localized portion of an arterial vessel. As the deposition increases, the inner diameter of the vessel becomes smaller (stenosis occurs) and impedes blood flow through the vessel. This reduction in blood throughput is harmful to the body and must be corrected. One method of correcting this arterial stenosis is to perform angioplasty using a balloon catheter, which involves inserting a catheter having at least a dilatation balloon into the stenotic area of the artery, inflating this balloon and expanding the inner diameter of the plaque-ridden segment of the artery.
An alternative variation of the above angioplasty method employs a catheter having two spaced-apart occlusion balloons whereby one of the balloons is a dilatation balloon used to expand the plaque-affected segment of the artery. Catheters having double occlusion balloons are disclosed, for example, in U.S. Pat. Nos. 5,836,967 and 5,279,546. After an initial expansion of the stenotic segment of the artery, the dilatation balloon is deflated and the catheter is manipulated and positioned such that the affected segment of the artery is between the two balloons. The two balloons are simultaneously pressurized and inflated, forming an enclosed, sealed space wherein the affected portion of the artery is contained within this space. In other words an occluded portion in the artery or lumen is formed. The catheter portion between the two balloons has a hole or plurality of holes for delivery of biologically active agents therethrough to variously treat the affected arterial segment. Thus, unlike a catheter having only a single balloon, the double-balloon catheter advantageously allows isolation of the affected segment and permits subsequent targeted application of beneficial agents to the affected arterial segment.
The double balloons thus function to seal off or occlude a section of the vessel apart from performing a dilatation function to expand the opening of a plaque-ridden, stenotic area of the vessel. During this occlusion step, the surfaces of the balloons contact healthy vessel tissue. Pressurizing and inflating the balloons to contact healthy endothelial or endoluminal tissue can cause injury to such tissue. The first kind of injury arises from abrading and compressing the surface cells of the inner vessel wall, which may lead to denuding of the surface, when the occlusion balloons are inflated. Denuding of the vessel wall may initiate the restenosis process. Another kind of injury, disruption of the internal elastic lamina, may be sustained because of the pressures that may be needed to provide a seal between the occlusion balloons and the vessel surfaces; this injury may result in distension of the vessel wall. Thus, certain balloon pressures may also cause injury to healthy vessel wall.
Hence, a comparative disadvantage of using a double-balloon catheter for delivery of biologically active agents is that the balloons must contact healthy portions of the inner wall of the vessel being treated, unlike a catheter with only a single dilatation balloon which generally only touches the plaque-covered vessel wall in their dilatation function of opening the stenotic segment. A double-balloon catheter, however, contacts not only the plaque-ridden part of the vessel during the dilatation step, but also touches at least two healthy, unaffected areas of the vessel during the occlusion step when both balloons are inflated. Accordingly, there exists a need for an improved double-balloon catheter that minimizes the denuding of healthy endothelial or endoluminal tissue due to abrasion and compression by the occlusion balloons when they are inflated.
The present invention applies to a catheter having two or more occlusion balloons wherein the balloons are spaced apart, and the balloons are simultaneously inflated to form a sealed space in a portion of a body lumen or an occluded portion in the body lumen. An object of the present invention is to provide a balloon catheter that reduces abrasion-type damage to healthy endothelial or endoluminal tissue.
Yet another object of the invention is to provide a double-balloon catheter having at least two balloons dispensing biologically active agents in the targeted area of the occluded portion of the body lumen situated between the occlusion balloons. Such balloons may provide superior sealing, can concurrently permit the use of comparatively lower balloon inflation pressures. The advantage of using lower pressures to achieve sufficient sealing is that the distension of the lumen wall may be reduced when the occlusion balloons are inflated.
Another object of the present invention is to provide a method to seal a targeted space within the body lumen which is to be treated with a biologically active agent, while facilitating more effective sealing and less injury to the endothelial or endoluminal wall. Moreover, by dispensing the biologically active agent in a targeted area that is effectively sealed, the present invention provides a more efficient and economical method of dispensing the biologically active agents and treating a body lumen.